(1) Field Of The Invention
This invention relates to a stabilizer for a floating platen used, for example, in a wire matrix printer.
(2) Background Information
In certain printers which are used in financial systems, for example, it is necessary for the printer to be able to print on media (a single sheet of paper or a passbook containing several sheets) having varying thicknesses. When such a requirement is made in a wire matrix printer environment, it is generally necessary that a forms compensation member be used. The forms compensation member is positioned close to the print head associated with the printer, and it is used to maintain a predetermined distance between the face of the print head and the top surface of the document to be printed upon. The platen associated with the printer is resiliently biased towards the face of the print head, with the top surface of the platen being spaced from the face of the print head by a distance which depends upon the thickness of the document. However, the forms compensation member keeps the face of the print head a predetermined distance from the top surface of the document being printed upon. Because the platen is not fixed relative to the face of the printer, it is referred to as a "floating platen".
One of the problems with a floating platen of the type mentioned above is that the top surface of the platen tends to tilt with respect to the face of the print head. This tilting occurs because the print head is located near the center of the platen and the associated forms compensation member is located close to the print head but to one side thereof. Because the forms compensation member applies its force near an edge of the platen, it causes the platen to tilt. When this occurs, the top surface of the platen is not parallel to the face of the print head; consequently, as the print head moves along the length of the platen in printing relationship therewith, it tends to produce defective printing by smudging the printing or causing a smudge line along the length of the platen. Generally an ink ribbon is located between the face of the printer and the top surface of the document to be printed upon.